NASA data · real observations · guided inquiry
Exoplanet Explorer uses the NASA Exoplanet Archive and mission catalogs to turn authentic telescope data into accessible visualizations, stories, and challenges.
Confirmed exoplanets
6,372
Years of discoveries
30+
The science behind the search
Turn NASA catalog measurements and telescope signals into questions you can investigate.
01 / Explore the worlds
Exoplanets orbit other stars, or in rare cases drift through space on their own. They range from small rocky worlds to gas giants larger than Jupiter. Some orbit in just a few days; others take far longer.
02 / Interpret the evidence
Exoplanets show that our Solar System is only one way planets can form and arrange themselves. We have found lava worlds such as 55 Cancri e and compact systems with several Earth-sized planets, such as TRAPPIST-1.
A guide to the catalog
Astronomers group exoplanets by size, temperature, and how they compare to planets we know. The Playground uses a simple classroom classifier: radius sets the main size family, while very hot or close-in planets are flagged as hot Neptune-like or hot Jupiter-like worlds.
Smaller than Earth. They are difficult to detect unless they orbit close to their stars, so the catalog contains fewer of them.
Roughly Earth-sized worlds. Size makes them interesting, but it does not prove they are rocky, wet, or habitable.
Larger than Earth but smaller than Neptune. Some may be rocky; others may have deep oceans or thick gas envelopes.
Bigger than super-Earths but smaller than Neptune. Many probably have thick atmospheres, and we do not have a close example in our Solar System.
Neptune-sized planets that orbit close to their stars or receive intense starlight. Their atmospheres can be strongly heated or stripped away.
Ice-giant-scale planets broadly similar in size to Uranus or Neptune, often with deep atmospheres and no solid surface like Earth.
Large Jupiter- or Saturn-scale planets dominated by gas. They are easier to detect than small rocky planets because of their size and mass.
Gas giants like Jupiter that orbit extremely close to their stars. They were among the first major surprises in exoplanet science.
Reading the signals
Exoplanets are small and faint compared to their stars, so astronomers often detect them indirectly through changes in starlight or stellar motion.
A planet passes in front of its star and blocks a tiny fraction of the starlight. Missions like Kepler and TESS watch for these repeating dips in brightness.
Example: Kepler-186 f
A planet's gravity makes its star wobble. By measuring tiny shifts in the star's spectrum, astronomers can infer the planet's presence and mass.
Example: 51 Pegasi b
Powerful telescopes block the star's light and directly capture the faint glow of giant planets, as the James Webb Space Telescope has begun to do.
Example: HR 8799 c
A foreground star and its planets act like a gravitational lens, briefly brightening a more distant star. These rare flashes can reveal planets thousands of light-years away.
Example: OGLE-2005-BLG-390L b
Astronomers measure a star's tiny side-to-side motion on the sky. This can reveal wider-orbit planets around nearby stars.
Example: Gaia astrometric planets
Tiny changes in a pulsar's clock-like radio pulses can reveal orbiting planets. This method found some of the first confirmed exoplanets.
Example: PSR B1257+12 planets
This is an independent educational project, not an official NASA or ESA product.